"""
收银台,练习
"""

a = float(input("请输入商品单价："))
b = int(input("请输入商品数量："))
c = float(input("支付金额："))

d = c - a * b

if d < 0:
    print("已付款：￥" + str(c) + "，还需付款：￥" + str(d.__abs__()))
elif d == 0:
    print("无需找零")
else:
    print("找零：￥" + str(d))
